Red Light Therapy for Achilles Tendonitis: Trials, Settings and Safety
Red light therapy for Achilles tendonitis has its clearest support as an add-on to calf loading exercise: in the best-known trial, athletes who added near-infrared light to their exercise programme had less pain at 4, 8 and 12 weeks than those given placebo light. Nearly all of this research used clinic lasers on the skin over the tendon. Below: the trials, mid-portion versus insertional pain, trial settings, exercise, ice and running, warning signs and panel set-up.
Key takeaways
- In a 2008 trial of 52 recreational athletes doing eccentric calf exercise, pain during activity at 8 weeks was 37.3 on a 100 mm scale with added 820 nm laser, against 62.8 with placebo. Stergioulas, 2008
- A 2022 review of 18 trials with 784 people with lower-leg tendon or heel pain found pain 18.15 mm lower on a 100 mm scale when laser was added to exercise. Naterstad, 2022
- A 2021 review of 17 trials with 835 people found tendon pain 1.06 points lower on a 10-point scale when red or near-infrared light was added to exercise. Tripodi, 2021
- In a 2006 placebo-controlled study of 7 people, 904 nm laser lowered an inflammatory marker next to the Achilles tendon 75 to 105 minutes after treatment. Bjordal, 2006, BJSM
- A sudden pop or snap at the back of the heel, with trouble pushing off or standing on tiptoe, can mean a rupture and needs medical help right away. Mayo Clinic
Does red light therapy for Achilles tendonitis help?
The research points to a benefit for pain when light is added to an exercise programme, rather than used on its own. The effect in the reviews is moderate, and the trials behind it are small.
Achilles tendonitis means pain and stiffness in the cord that joins the calf muscles to the heel bone; physiotherapists often call it tendinopathy. Three reviews have pooled the light trials.
| Review | What it pooled | Main finding |
|---|---|---|
| Tumilty, 2010 | Laser trials on tendinopathy, searched to 2008 | Achilles pain about 13.6 mm lower on a 100 mm scale |
| Tripodi, 2021 | 17 trials, 835 people, one of them Achilles | Pain 1.06 points lower on 10 with light plus exercise |
| Naterstad, 2022 | 18 trials, 784 people: 11 heel pain, 5 Achilles, 2 knee tendon | Pain 14.98 mm lower at recommended doses; 19.67 mm lower at 9 weeks as an add-on to exercise |
The 2022 review found that laser "significantly reduces pain and disability" in lower-leg tendon and heel pain, in the short and medium term. Naterstad, 2022 Our guide to red light therapy for tendonitis covers the elbow, shoulder and wrist trials.
What did the Achilles light trials find?
The best-known positive trial found faster pain relief when 820 nm laser was added to eccentric calf exercise. A 2016 trial of 80 people found the group that had laser plus twice-weekly calf exercise improved most at 12 weeks.
In the research, the term is low level laser therapy: Achilles tendinopathy trials used small clinic lasers held on the skin over the tendon.
In the 2008 trial, 52 recreational athletes with long-standing Achilles pain all did eccentric exercise. Stergioulas, 2008 Half also had 820 nm laser on 6 points along the tendon, 12 sessions over 8 weeks. The other half had placebo light.
- 4 weeks: pain during activity 53.6 with laser, 71.5 with placebo (100 mm scale).
- 8 weeks: 37.3 against 62.8.
- 12 weeks: 33.0 against 53.0.
The laser group at 4 weeks was about where the placebo group was at 12.
The 2016 trial compared twice-daily and twice-weekly exercise, each with laser or placebo. Tumilty, 2016 The authors wrote that adding light "can bring added benefit".
In a smaller study, seven people with tendinitis in both Achilles tendons had 904 nm laser and placebo laser, given in random blinded order. Bjordal, 2006, BJSM An inflammatory marker next to the tendon fell after the active laser: a mechanism over a couple of hours, not recovery.
Does light help mid-portion and insertional Achilles pain the same way?
The Achilles light trials enrolled people with long-standing pain, mostly in the middle of the tendon. For pain where the tendon meets the heel, the closest evidence comes from the heel pain trials in the 2022 review.
The American Academy of Orthopaedic Surgeons describes two types. AAOS
- Mid-portion (noninsertional): pain and thickening in the middle of the tendon, above where it joins the heel. Common in younger, active people, especially runners.
- Insertional: pain where the tendon joins the back of the heel bone, often with bone spurs.
The AAOS says heel drops off a step suit mid-portion pain but "should not be done for insertional" pain, so a physiotherapist should set the programme. RUH Bath also suggests softer heel cups or gel heel pads for the insertional type.
Where you aim the light differs too: the thickened middle of the tendon for mid-portion pain, the back of the heel for insertional pain.
Red light or near-infrared: which wavelengths were used on the Achilles?
The Achilles trials that published their settings used near-infrared: 820 nm, 810 nm or 904 nm. The tendon sits just under the skin, and the reviews found their results with near-infrared light.
The World Association for Laser Therapy (WALT) dose table for the Achilles covers lasers from 780 to 860 nm. WALT, 2010
Red light can run alongside near-infrared on a multi-wavelength panel, which covers the whole tendon rather than a few laser points. Our comparison of cold laser therapy vs red light therapy explains the difference.
What settings did the Achilles light trials use?
Trials gave a few joules over several points on the tendon, about 12 sessions over 4 to 8 weeks, mostly alongside exercise. WALT suggests daily sessions for 2 weeks or every other day for 3 to 4 weeks.
| Study | Light | Dose | Sessions | Weeks | With exercise? |
|---|---|---|---|---|---|
| Bjordal, 2006 (placebo, 7 people) | 904 nm laser | 5.4 J per point | 1 | Single session | No, activity just before |
| Stergioulas, 2008 (placebo, 52 people) | 820 nm laser | 5.4 J per session over 6 points | 12 | 8 | Yes, eccentric |
| Tumilty, 2008 pilot (placebo, 20 people) | 810 nm laser | 3 J per point, 6 points, 30 seconds each | 3 a week | 4 (exercise 12) | Yes, eccentric |
| WALT, 2010 guidance | 780 to 860 nm laser | 8 J over 2 to 3 points | Daily, or every other day | 2, or 3 to 4 | Not stated |
The pilot settings come from Tumilty, 2008. Clinic laser joules per point do not convert into panel minutes, but the pattern carries over: near-infrared on the whole tendon, regular sessions for several weeks, alongside exercise.
Can red light replace heel drops and calf raises?
No. Loading exercise is the main treatment for Achilles tendinopathy, and in the positive Achilles trials the light was added to it.
Results across the small Achilles light trials vary, and current physiotherapy guidance puts loading exercise first and does not recommend low-level laser as a main treatment for mid-portion pain. JOSPT, 2024
An NHS physiotherapy leaflet sets out the kind of programme light sits beside. RUH Bath
- Exercises: seated heel raises with weight, heel raises on two legs and then one, with the knee straight and bent, building to small hops.
- Tempo: 3 seconds up, a 2-second hold, 3 seconds down.
- Duration: keep going for at least 3 to 4 months.
Should you use red light before or after calf exercises?
The trials do not settle the order. A session on the same day as your physio exercises, either before or after them, fits how the trials combined the two.
In the 2006 study, the tendons were lit after pain-provoking activity. Pick one order and keep it for 3 to 4 weeks, so your log compares like with like.
Ice, heat or red light for an Achilles flare?
Mayo Clinic suggests ice for a sudden injury and says heat may help more with ongoing tendon pain. Keep ice and light as separate sessions, and let the skin return to its normal temperature in between.
For a sudden injury, Mayo advises ice for 15 to 20 minutes every 4 to 6 hours, with a cloth between ice and skin. Mayo Clinic For ongoing tendinopathy, "Heat may be more helpful."
A newly injured, hot or swollen tendon is not the time to start light. Our guide to red light therapy for injuries suggests no heat, including a warm panel, for the first 2 to 3 days.
Can you keep running with Achilles tendonitis while using red light?
Often yes, at a reduced level, as long as pain settles within a few hours. Light is not a way to train through pain.
The RUH Bath leaflet advises limiting long walks and running for about six weeks, then rebuilding over a month or two. RUH Bath
- Pain rule: pain that rises with exercise "should settle within a few hours"; if it lasts longer, work at a lower level next time.
- Return to running: once you can walk several miles and do the exercises without aggravating the tendon.
For other running pain in the lower leg, see red light therapy for shin splints.
How long before Achilles pain eases with light and exercise?
Expect a few months for the tendon itself. In the 2008 trial, the light group's pain at 4 weeks matched the placebo group's at 12 weeks.
Cleveland Clinic says "It may take a few months for the pain to get better." Cleveland Clinic
The RUH Bath leaflet says most people "recover over 12 months or less", with gradual improvement along the way.
Judge a home light routine at 3 to 4 weeks with the same settings. Score first-steps pain in the morning out of 10, and pain during a set number of heel raises.
Which Achilles symptoms need a doctor before any light?
A sudden pop or snap, a feeling of being kicked in the calf, or being unable to push off or stand on tiptoe can mean a rupture and needs urgent care first. Severe pain, pain that stops you moving the foot, or pain that does not improve after a few weeks also needs checking.
- Possible rupture: Mayo advises talking to a healthcare professional "right away if you hear a pop in your heel". Mayo Clinic
- No progress: Cleveland Clinic suggests seeing a provider if pain does not improve after a few weeks or is severe.
- Calf swelling: a swollen, painful, red or darkened calf can mean a clot and needs urgent advice.
- Antibiotics: ciprofloxacin and related antibiotics raise the risk of tendinitis and tendon rupture, during treatment or for up to several months afterwards. MedlinePlus Tell your prescriber about any new tendon pain.
- Injections: the AAOS says cortisone injections into the Achilles are not recommended because they can cause rupture; ask your doctor before using light on an injected area.
Ciprofloxacin can also make skin sensitive to sunlight, and so can painkillers such as ibuprofen or naproxen. Our precautions rule out use with photosensitising medication, so anyone taking a medicine should check with their pharmacist or doctor before using the device.
After a rupture or surgery, light is only for once the doctor or surgeon agrees, over closed, intact skin. Never take off a boot or cast to use light. With metal implants, ask your surgeon first.
How do you use a Kivorla panel on the Achilles tendon?
Sit or lie with the back or side of your lower leg towards the panel so the tendon, heel to calf, faces it at about 6 inches, with the goggles on. Run the near-infrared and red channels for 10 to 15 minutes, three to five times a week, alongside your exercises, and judge it at 3 to 4 weeks.
The 9-Spectrum Red Light Therapy Panel carries 480, 590, 630, 660, 670, 810, 830, 850 and 1060 nm, each dimmable from 1 to 100%. Its 810, 830 and 850 nm channels sit inside the WALT 780 to 860 nm band, either side of the 820 nm Achilles trial. The mask is a face device and does not reach the leg.
- Set-up: stand the panel upright on the floor, or hang it low on a door or wall with the included door hook, pulley, hanging cables and screws.
- Position: lie face down with the back of the lower leg towards the panel, or sit side-on with the inner or outer ankle towards it, which keeps the light off your face.
- Distance: about 6 inches once you are used to it. In the first week it is fine to start further back, at about 12 inches, with a shorter timer and dimmed channels.
- Channels: 810, 830 and 850 nm high; 630, 660 and 670 nm on; 1060 nm optional; 480 and 590 nm off; continuous light.
- Timer: 10 to 15 minutes. If no time is set, the panel stops at 5 minutes. The surface stays at or below 40°C.
- Skin: bare skin, with socks, tape and sleeves off; skip any blister or broken skin. Warm is fine; hot means step back or stop.
- Eyes: goggles on even at foot level, eyes closed, and never look into the panel. See our guide to red light therapy goggles.
The laser trials gave small doses at a few points. To stay closer to that range, use a shorter timer (it starts at 1 minute), turn the channels down from 100%, or step back to 12 inches. Leave at least 6 hours between 30-minute sessions. The controller and goggles are included.
Our precautions rule the panel out during pregnancy, breastfeeding or preparing for pregnancy, with epilepsy or light-triggered seizures, a thyroid condition or thyroid medication, sunburn on the body in the past 2 weeks, or Fitzpatrick skin type V or VI, and while asleep.
Read the precautions before ordering. Standard shipping to the US, UK and Germany is free. Under our return and refund policy, returns are accepted within 30 days: an unopened device with its seals intact is refunded less a 10% restocking fee, and an opened device that is undamaged and complete is refunded less 20%.
Kivorla devices are general wellness devices, not medical devices, and are not intended to treat Achilles tendonitis. See a doctor or physiotherapist for a sudden pop, severe pain or pain that is not improving, and keep the exercise plan your physiotherapist sets.